Display screen or portion thereof with transitional graphical user interface



FIG. 1 is the first image in a sequence for a display screen or portion thereof with transitional graphical user interface showing our new design;

FIG. 2 is the second image thereof;

FIG. 3 is the third image thereof;

FIG. 4 is the fourth image thereof;

FIG. 5 is the fifth image thereof;

FIG. 6 is the design of FIG. 1 with environmental portions removed;

FIG. 7 is the design of FIG. 2 with environmental portions removed;

FIG. 8 is the design of FIG. 3 with environmental portions removed;

FIG. 9 is the design of FIG. 4 with environmental portions removed; and,

FIG. 10 is the design of FIG. 5 with environmental portions removed.

The appearance of the graphical user interface transitions between the images shown in FIGS. 1-5 and FIGS. 6-10. The order, process, or period in which one image transitions to another forms no part of the claimed design. The broken line showing of the text, various symbols, display screen, and remainder of the graphical user interface forms no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 